A standard baler has a system for compacting crushable material, for instance cut crop or waste paper, into a generally parallepipedal mass that is moved in the machine along a square-section passage. A plurality of knotters such as described in German utility model 90 15 883 published Nov. 22, 1990 and in U.S. Pat. Nos. 4,506,920 and 4,511,165 are provided in a row in the passage and act along with string- or wire-feeding devices to secure respective loops of string or wire around the bale which is then ejected from the baler. Normally four to six such loops are used to make the bale coherent enough to handle.
The knotters are all mounted coaxially on a common shaft. Each knotter comprises a drive disk having a hub fixed to the shaft and a partially toothed rim that engages one or more gears carried on a knotter support that is journaled on the hub of the respective disk and also fixed against rotation on the frame of the baler. Thus as the shaft rotates the teeth of its disk engage and disengage the gears of the knotter mechanism carried on the support and effect the various well known movements of this mechanism to catch and tie the ends of the strand looped around the bale.
The knotters are subject to considerable wear since they function in a particle-filled environment and are often working with a metallic or synthetic-resin tie strand that also subjects its parts to considerable wear. It is nonetheless an extremely onerous job to uncouple one end of the drive shaft and slip off one or more knotters so they can be worked on. Thus it is standard to make the knotter support in a pair of halves that are bolted together around the hub of the respective main drive disk. The support can therefore be separated into two halves by withdrawing some bolts to separate it from its drive disk and replace its parts and/or service it.
As the disk itself is also subject to wear, the Cormick system used in Fortschritt balers sold under models K441 and K441/1 use a drive disk formed with diametral grooves allowing it to be split into two parts and removed if necessary. A replacement disk is similarly split in half and secured together by screws so that the entire shaft does not have to be pulled to service a single knotter. Since, however, such a disk is used to transmit considerable torque in stop-and-go movements and must fit very accurately with the mechanism of the knotter, such reassembled disks often are unsatisfactory. Without a perfect fit, the knotter can be counted on to wear prematurely and fail rapidly.